What is the impact of using the word “type” in patent claims?

This page is an FAQ based on guidance from the Manual of Patent Examining Procedure. It is provided as guidance, with links to the ground truth sources. This is information only: it is not legal advice.

The use of the word “type” in patent claims can extend the scope of an expression and potentially render it indefinite. According to MPEP 2173.05(b), “The addition of the word ‘type’ to an otherwise definite expression (e.g., Friedel-Crafts catalyst) extends the scope of the expression so as to render it indefinite.” For example, in Ex parte Copenhaver, the addition of “type” to a definite expression was found to render the claim indefinite. Similarly, in Ex parte Attig, the phrase “ZSM-5-type aluminosilicate zeolites” was held indefinite because it was unclear what “type” was intended to convey.